Association between ABO blood group and risk of Crohn’s disease: A case‐control study in the Chinese Han population

BACKGROUND: Blood group O has been reported to be a potentially protective factor for Crohn's disease (CD) susceptibility in Caucasian and Korean populations, but a similar conclusion was not found in a Chinese study. The present study investigated the potential association in the Chinese Han population. METHODS: We included 275 CD patients, 132 ulcerative colitis (UC) patients and 1201 healthy individuals in this case‐control study. The demographic characteristics and ABO blood group were compared among the three groups. The clinical characteristics and treatment of CD were further investigated according to the blood group distribution. RESULTS: The blood group distribution in CD patients was significantly different from healthy controls, and the frequency of O blood in CD patients was significantly lower compared to healthy controls. After adjusting for age and gender, the non‐O blood groups remained significantly associated with CD susceptibility in propensity score‐adjusted and propensity score‐matched analyses. Compared to CD patients with non‐O blood groups, patients with O blood were at a lower risk of developing penetrating disease, more likely to receive immunosuppressant treatment and less likely to receive biological treatment. CONCLUSION: Our results confirmed that non‐O blood groups were significantly associated with an increased risk of CD in the Chinese Han population.